Assessment of Family-Reported Medication Adherence
Assessment of Family-Reported Medication Adherence
The current study is the first to use and compare two different methods of developing empirically derived correction factors for parent-reported medication adherence. Further, the current study is the first to illustrate the development of such correction factors for children with IBD. Given that the problem of self or parent-reported adherence overestimation is common across pediatric populations, this correction factor methodology could be more broadly applied to other illness groups. In relation to clinical practice, the correction factor approach is a first step toward allowing providers to continue to use self- or parent-report of adherence, which often is most feasible to implement, while providing a more accurate adherence assessment that could be used to identify families who could benefit from adherence promotion interventions.
Consistent with prior literature comparing adherence assessed by subjective versus objective methods in IBD and other chronic illness populations, the current results demonstrated that, while parent-reported and EM adherence are correlated, parent-reported adherence is significantly higher than EM adherence (Greenley et al., 2012; Hommel et al., 2009; Shi et al., 2010). In addition, the results suggested that, consistent with prior results for children with chronic conditions (Modi et al., 2011), an EM-based 90% adherence cut-point defining "adherent" versus "non-adherent" for pediatric IBD patients has the highest sensitivity and specificity when comparing EM and parent-reported adherence. Using the 90% cut-point, patients who were "non-adherent" had significantly larger discrepancies between parent-reported and EM adherence than those who were "adherent." This finding indicates that parent-reported adherence is more likely to be inflated for patients who have lower levels of objectively measured adherence. Thus, application of a correction factor to adjust for inflated parent-reported adherence is particularly important for these patients with lower adherence levels (i.e., <90% using EM assessment).
The current study yielded preliminary findings on two potential methods for correcting parent-reported adherence levels to maximize their accuracy. Applied in a clinical setting, these two methods would be used in the following way: If a parent reported that their child missed 5 out of 14 doses in the last week, this would indicate a parent-reported adherence level of 64% ([14 − 5]/14 = .64). The first method would entail multiplying parent-reported adherence by 1.04 and subtracting 12.46 to yield a corrected adherence level of 54.1%. The second method would entail multiplying parent-reported adherence levels by .924 (64 × .924) to yield a corrected adherence level of 59%. Although neither of these correction factor methods is better than the other mathematically, the second method (i.e., multiplying parent-reported adherence by .924) is more feasible for use in clinical practice, given that it requires a single calculation. Also, while this would need to be examined in other pediatric populations, the corrected adherence values obtained by the two methods are highly similar.
The current study had several strengths. First, this study used multiple methods of assessing adherence (i.e., parent-report and EM) and compared adherence estimates across these methods. Second, the use of EM is a strength because it is argued to be a more accurate and objective assessment of adherence, which can describe patterns of adherence over time (Hommel et al., 2008b; La Greca & Bearman, 2003; Rapoff, 2010). Third, this study included participants with a demographic background similar to other patients with IBD in previously published studies (Mackner & Crandall, 2007). And finally, this study is the first within a pediatric IBD sample to develop correction factors for parent-reported adherence that could be used in clinical practice to increase accuracy of adherence estimates.
A few important study limitations should be noted, including the fact that adherence was monitored over a limited span of time (i.e., 2 weeks). It is possible that longer monitoring periods are needed to fully assess the changing nature of adherence over time. It will therefore be important to replicate the current findings by assessing adherence for a longer period of time and examining longitudinal patterns of adherence. Although most studies of youth with IBD have included similar or smaller sample sizes, future studies examining youth across multiple sites and including non-English speaking and lower income families will increase the generalizability of findings. Finally, the adherence levels obtained in the current study are higher than some reported in the literature (Hommel et al., 2009). Adherence has been assessed in a variety of ways among youth with IBD and prior estimates vary from 50–92% (Greenley et al., 2012; Hommel et al., 2009). While participant reactivity to monitoring leading to higher-than-normal levels of adherence is a potential, reactivity was most likely not a strong contributor to the EM adherence levels in the current study due to the fact that EM adherence data was taken from a 2-week period that was 6 weeks post-study enrollment. As discussed in a previous report, the higher adherence rates obtained in the current sample may be due to participants opening their MEMS bottles when taking all medications rather than only the medication being monitored (Hommel et al., 2012). Consequently, our example correction factors may provide conservative corrected values.
The empirically derived correction factors in this study should be confirmed by future research and the concept of the correction factor extended to other pediatric populations. If confirmed and further tested, correction factors have several potential clinical implications. Correction factors could be used in routine clinical practice to adjust subjectively reported adherence levels, which may guide medical treatment (e.g., decisions to change dosages) and interventions to address poor adherence. For instance, providers could use corrected adherence levels to determine whether a patient and his/her family may need intervention targeting medication adherence and providers might tailor interventions to different levels of non-adherence. Alternatively, a low-corrected adherence level could be further examined with longitudinal adherence monitoring to better understand a particular child's or family's patterns of non-adherence prior to beginning clinical intervention. We recommend that correction factors for self- or parent-reported adherence be used in combination with other adherence assessment methods (e.g., blood assays).
The correction factor methods illustrated by the current study provide corrected adherence levels, which could be used as a more accurate approximation of a patient's medication adherence. These corrected adherence levels should not, however, be considered to be exact or "true score" adherence levels for individual patients. Instead, the corrected adherence levels could be used to guide decisions about further assessment and intervention, as described above. This issue is particularly relevant at the extremes of adherence. At the upper limit of adherence (i.e., parent reports 100% adherence), the correction factors used in the current study will inevitably lead to adherence levels below 100%. While this may appear to penalize families who, indeed, are 100% adherent, clinically, these families' corrected adherence levels would not suggest that they are in need of further adherence assessment or intervention. On the other extreme, a family reporting very low adherence could have a very low corrected adherence level, including one that is numerically negative. In our view, these very low levels of adherence (including negative adherence values, which are not meaningful alone) would indicate that the patient and family likely would benefit from adherence promotion interventions.
Our results also have implications for future research on adherence. Further work is needed to establish and test similar correction factors for adolescent and young adult self-reported adherence. This work could also assess the degree of responsibility different family members have for medication adherence, given that adolescence is a time during which allocation of treatment responsibilities may change (Pai et al., 2010). Integrating multiple reporters and methods of assessing adherence is critical (Quittner, Modi, Lemanek, Ievers-Landis, & Rapoff, 2008). Thus, while continuing to examine the use of correction factors for subjectively reported adherence will be important, future research could also explore the integration of corrected subjectively reported adherence with other adherence assessment methods, such as drug assays and direct observation of adherence. For example, it will be important to investigate the extent to which corrected levels of subjectively reported adherence are consistent with adherence levels obtained by other assessment methods. In addition, future studies could investigate adherence to other IBD medications to compare adherence to those medications with adherence to the primary IBD medications which were examined in the current study. Future work could also examine the link between varying levels of non-adherence (both corrected and uncorrected) and health outcomes (e.g., disease severity or symptoms) in order to identify the particular adherence cutoffs that could be used to define "non-adherence." In addition, there is a growing literature demonstrating that numerous factors contribute to the medication adherence of children. For example, for children with IBD and their families, family functioning, barriers to adherence, and patient coping, emotional functioning, and quality of life have been shown to be related to adherence (Gray, Denson, Baldassano, & Hommel, 2012; Hommel, Davis, & Baldassano, 2008a; Mackner & Crandall, 2005). Incorporating assessment of these contributors to medication adherence will create a more complete picture of the factors influencing adherence and could, potentially, be used to adjust for the upwards bias typical of subjectively-reported adherence. Increasing the accuracy of adherence assessments will facilitate better-informed clinical decision making, including the implementation of interventions to promote adherence.
Discussion
The current study is the first to use and compare two different methods of developing empirically derived correction factors for parent-reported medication adherence. Further, the current study is the first to illustrate the development of such correction factors for children with IBD. Given that the problem of self or parent-reported adherence overestimation is common across pediatric populations, this correction factor methodology could be more broadly applied to other illness groups. In relation to clinical practice, the correction factor approach is a first step toward allowing providers to continue to use self- or parent-report of adherence, which often is most feasible to implement, while providing a more accurate adherence assessment that could be used to identify families who could benefit from adherence promotion interventions.
Consistent with prior literature comparing adherence assessed by subjective versus objective methods in IBD and other chronic illness populations, the current results demonstrated that, while parent-reported and EM adherence are correlated, parent-reported adherence is significantly higher than EM adherence (Greenley et al., 2012; Hommel et al., 2009; Shi et al., 2010). In addition, the results suggested that, consistent with prior results for children with chronic conditions (Modi et al., 2011), an EM-based 90% adherence cut-point defining "adherent" versus "non-adherent" for pediatric IBD patients has the highest sensitivity and specificity when comparing EM and parent-reported adherence. Using the 90% cut-point, patients who were "non-adherent" had significantly larger discrepancies between parent-reported and EM adherence than those who were "adherent." This finding indicates that parent-reported adherence is more likely to be inflated for patients who have lower levels of objectively measured adherence. Thus, application of a correction factor to adjust for inflated parent-reported adherence is particularly important for these patients with lower adherence levels (i.e., <90% using EM assessment).
The current study yielded preliminary findings on two potential methods for correcting parent-reported adherence levels to maximize their accuracy. Applied in a clinical setting, these two methods would be used in the following way: If a parent reported that their child missed 5 out of 14 doses in the last week, this would indicate a parent-reported adherence level of 64% ([14 − 5]/14 = .64). The first method would entail multiplying parent-reported adherence by 1.04 and subtracting 12.46 to yield a corrected adherence level of 54.1%. The second method would entail multiplying parent-reported adherence levels by .924 (64 × .924) to yield a corrected adherence level of 59%. Although neither of these correction factor methods is better than the other mathematically, the second method (i.e., multiplying parent-reported adherence by .924) is more feasible for use in clinical practice, given that it requires a single calculation. Also, while this would need to be examined in other pediatric populations, the corrected adherence values obtained by the two methods are highly similar.
The current study had several strengths. First, this study used multiple methods of assessing adherence (i.e., parent-report and EM) and compared adherence estimates across these methods. Second, the use of EM is a strength because it is argued to be a more accurate and objective assessment of adherence, which can describe patterns of adherence over time (Hommel et al., 2008b; La Greca & Bearman, 2003; Rapoff, 2010). Third, this study included participants with a demographic background similar to other patients with IBD in previously published studies (Mackner & Crandall, 2007). And finally, this study is the first within a pediatric IBD sample to develop correction factors for parent-reported adherence that could be used in clinical practice to increase accuracy of adherence estimates.
A few important study limitations should be noted, including the fact that adherence was monitored over a limited span of time (i.e., 2 weeks). It is possible that longer monitoring periods are needed to fully assess the changing nature of adherence over time. It will therefore be important to replicate the current findings by assessing adherence for a longer period of time and examining longitudinal patterns of adherence. Although most studies of youth with IBD have included similar or smaller sample sizes, future studies examining youth across multiple sites and including non-English speaking and lower income families will increase the generalizability of findings. Finally, the adherence levels obtained in the current study are higher than some reported in the literature (Hommel et al., 2009). Adherence has been assessed in a variety of ways among youth with IBD and prior estimates vary from 50–92% (Greenley et al., 2012; Hommel et al., 2009). While participant reactivity to monitoring leading to higher-than-normal levels of adherence is a potential, reactivity was most likely not a strong contributor to the EM adherence levels in the current study due to the fact that EM adherence data was taken from a 2-week period that was 6 weeks post-study enrollment. As discussed in a previous report, the higher adherence rates obtained in the current sample may be due to participants opening their MEMS bottles when taking all medications rather than only the medication being monitored (Hommel et al., 2012). Consequently, our example correction factors may provide conservative corrected values.
The empirically derived correction factors in this study should be confirmed by future research and the concept of the correction factor extended to other pediatric populations. If confirmed and further tested, correction factors have several potential clinical implications. Correction factors could be used in routine clinical practice to adjust subjectively reported adherence levels, which may guide medical treatment (e.g., decisions to change dosages) and interventions to address poor adherence. For instance, providers could use corrected adherence levels to determine whether a patient and his/her family may need intervention targeting medication adherence and providers might tailor interventions to different levels of non-adherence. Alternatively, a low-corrected adherence level could be further examined with longitudinal adherence monitoring to better understand a particular child's or family's patterns of non-adherence prior to beginning clinical intervention. We recommend that correction factors for self- or parent-reported adherence be used in combination with other adherence assessment methods (e.g., blood assays).
The correction factor methods illustrated by the current study provide corrected adherence levels, which could be used as a more accurate approximation of a patient's medication adherence. These corrected adherence levels should not, however, be considered to be exact or "true score" adherence levels for individual patients. Instead, the corrected adherence levels could be used to guide decisions about further assessment and intervention, as described above. This issue is particularly relevant at the extremes of adherence. At the upper limit of adherence (i.e., parent reports 100% adherence), the correction factors used in the current study will inevitably lead to adherence levels below 100%. While this may appear to penalize families who, indeed, are 100% adherent, clinically, these families' corrected adherence levels would not suggest that they are in need of further adherence assessment or intervention. On the other extreme, a family reporting very low adherence could have a very low corrected adherence level, including one that is numerically negative. In our view, these very low levels of adherence (including negative adherence values, which are not meaningful alone) would indicate that the patient and family likely would benefit from adherence promotion interventions.
Our results also have implications for future research on adherence. Further work is needed to establish and test similar correction factors for adolescent and young adult self-reported adherence. This work could also assess the degree of responsibility different family members have for medication adherence, given that adolescence is a time during which allocation of treatment responsibilities may change (Pai et al., 2010). Integrating multiple reporters and methods of assessing adherence is critical (Quittner, Modi, Lemanek, Ievers-Landis, & Rapoff, 2008). Thus, while continuing to examine the use of correction factors for subjectively reported adherence will be important, future research could also explore the integration of corrected subjectively reported adherence with other adherence assessment methods, such as drug assays and direct observation of adherence. For example, it will be important to investigate the extent to which corrected levels of subjectively reported adherence are consistent with adherence levels obtained by other assessment methods. In addition, future studies could investigate adherence to other IBD medications to compare adherence to those medications with adherence to the primary IBD medications which were examined in the current study. Future work could also examine the link between varying levels of non-adherence (both corrected and uncorrected) and health outcomes (e.g., disease severity or symptoms) in order to identify the particular adherence cutoffs that could be used to define "non-adherence." In addition, there is a growing literature demonstrating that numerous factors contribute to the medication adherence of children. For example, for children with IBD and their families, family functioning, barriers to adherence, and patient coping, emotional functioning, and quality of life have been shown to be related to adherence (Gray, Denson, Baldassano, & Hommel, 2012; Hommel, Davis, & Baldassano, 2008a; Mackner & Crandall, 2005). Incorporating assessment of these contributors to medication adherence will create a more complete picture of the factors influencing adherence and could, potentially, be used to adjust for the upwards bias typical of subjectively-reported adherence. Increasing the accuracy of adherence assessments will facilitate better-informed clinical decision making, including the implementation of interventions to promote adherence.
